In customary windshield wiper devices, whether they comprise a motor controlling a transmission mechanism comprising a variety of connecting rods and cranks operating a drive shaft for a windshield wiper arm equipped with a windshield wiper blade capable of wiping against a glazed surface, such as a windshield of a motor vehicle, or whether they involve a geared motor fitted with a motor driving a reduction gear equipped with a reduction system driving a connecting rod system operating an output shaft directly driving the windshield wiper arm and blade, or indirectly driving this arm-blade unit by means of such a transmission mechanism, there is still the problem of controlling the wiping angle with the greatest precision possible.
As is known, the wiping angle of the windscreen wiper arm-blade unit, i.e. the angle which this unit travels from one extreme position to another, is determined either by a particular arrangement of the connecting rods and cranks of the transmission mechanism or of the connecting rod system of the geared motor, or by the electric motor itself.
Bearing in mind firstly the clearance necessary for the operation of the connecting rod system or of the transmission mechanism and secondly the inertia of the arm-blade unit during its wiping travel, this theoretical wiping angle is normally exceeded; this may result in a malfunction, for example the windshield wiper blade may knock against one of the edges of the surface to be wiped and cause the destruction of the blade itself, and/or generate noise which discomforts the user.
It has been proposed partially to resolve this problem in the case of a geared motor device in DE-A-3,740,312, in which an angle damper is provided between a fixed part of the geared motor and a mobile part of the connecting rod system thereof, such as the output shaft.
Although this arrangement is generally satisfactory, it has been observed that this damper involves a larger radial space requirement at the level of the connection of the shaft, and requires specific arrangements for each type of geared wheel.
In practice, an elastomer material is disposed between a gear wheel carried by the crank of the connecting rod system and the base of a substantially semi-circular groove in the fixed part of the housing, the groove being concentric with the shaft.
These arrangements are very elaborate, very difficult to perform and require, during mounting, a very precise and meticulous assembly operation, which is detrimental to the cost price of the product.